VisualVM is a visual tool integrating several commandline JDK tools and lightweight profiling capabilities. Designed for both production and development time use, it further enhances the capability of monitoring and performance analysis for the Java SE platform.
JMeasurement is a free and simple java api for monitoring runtime and usage (count, parallel activation, last activation) of user defined points in java production code. It is simple to use and extended. JMX is supported.
Stopwatch was ment to replace System.currentTimeMillis() calls, match like Log4j replaced System.out.println() calls. To see how it does that go to Quick Start page.
An application seems to run more slowly than it should or more slowly than it did previously, or the application is unresponsive or hangs. You may encounter these situations in production or during development. What is at the root of these problems? Often
Jconsole is a JMX-compliant monitoring tool. It uses the extensive JMX instrumentation of the Java virtual machine to provide information on performance and resource consumption of applications running on the Java platform.